With the increase of traffic, the problems of reducing the specific consumption of fuel and atmospheric pollution are becoming more and more serious.
As regards the four-stroke motor, progress made in both diesels and controlled ignition motors, particularly electronic, has led to impressive results which are being constantly improved.
The difficulty with the four-stroke motor is that to allow for good operating conditions, it is necessary to have all sorts of complicated, costly, relatively burdensome accessories, which are economically understood only if the effective power is relatively high to begin with.
The four-stroke motor can thus be considered as specifically meeting the current needs of the automobile. On the other hand, this motor is not well suited for motorcycles, with the exception of those with very large cubic capacity, and it is inconceivable to use it in the case of light-weight motorcycles.
With respect to motorcycles with small cubic capacity and small powers, the two-stroke motor seems far better suited. Indeed, because of its simpler technological conception as opposed to that of the four-stroke motor, the two-stroke motor makes it possible to produce small amounts of power with reduced cumbersomeness, weight and cost price.
With respect to utilization performance, efficiency is generally inferior to that of a four-stroke motor. However, in view of the low power levels considered and the ensuing low degree of consumption, this problem is not crucial.